The invention relates to a method for operating a drive device for a motor vehicle.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
The drive device serves for driving the motor vehicle, i.e., for providing a torque that is directed toward driving the motor vehicle. The drive device has an internal combustion engine, which can produce the torque either by itself or in cooperation with at least one further drive aggregate. The internal combustion engine can be operatively connected with the at least one wheel of the motor vehicle, in particular with a wheel axle of the motor vehicle on which the wheel is mounted. This purpose is served by the shifting clutch, which is present in the operative connection.
The term shifting clutch means any element, which can be present in at least two different shifting states, wherein in one of the shifting states the operative connection between the internal combustion engine and the wheel is present and in another one of the shifting states the operative connection is interrupted. Generally speaking the shifting coupling is thus a releasable clutch, in particular a releasable force fitting clutch. For example the shifting clutch is a starting element, preferably a starting clutch, a torque converter, in particular a hydrodynamic torque converter, or the like.
When the shifting clutch is open the operative connection between the internal combustion engine and the wheel is interrupted. On the other hand when the shifting clutch is at least partially closed the torque is transmitted from the internal combustion engine to the wheel. When the shifting clutch is completely closed the operative connection between the internal combustion engine and the wheel is preferably rigid or at least almost rigid. Thus when the shifting clutch is completely closed ideally no clutch slip of the clutch occurs.
Starting the internal combustion engine requires to first drag the internal combustion engine to a defined start rotational speed. For this purpose the electric machine is provided which is for example configured as a starter or a starter generator. The electric machine can be permanently operatively connected with the internal combustion engine, i.e., in such a manner that a torque that serves for staring the internal combustion engine is transmitted by the electric machine to the internal combustion engine but on the other hand the running internal combustion engine does not drag the electric machine.
It would be desirable and advantageous to provide a method for operating a drive device for a motor vehicle, which has advantages compared to known methods and enables an efficient and fuel-saving operation of the drive device or the internal combustion engine.